Re: A low inductance MMC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Finn,

Perfect example where the relative lead (and cap) 
inductance can be significant enough to alter 
tuning when the primary L is low making this 
external inductance appear large. It looks like 
maybe only 3/4" between series'd caps, but of 
course the cap body is a large part of the 
inductance. I don't know if Terry or someone 
knows a trick to reduce cap inductance, but it 
looks to be like you did a good job at trying to 
reduce as much cap L as possible.

Take care,
Bart

Tesla list wrote:

> Original poster: Finn Hammer <f-h@xxxx>
>
> All,
>
> A while ago I designed an attempt at a low 
> inductance MMC. It is for OLTC service, so a 
> small inductance is important, because the 
> inductance of the coil`s one turn primary only is 374nH.
>
> The idea was to create a return path from the 
> far end of the capacitor strings back to the 
> start of the strings, which would eliminate the 
> loop area of the return by distributing it within the pack of strings.
>
> When I fitted it to the coil, I had to remove 
> 3µF out of 17µF to tune the coil, which means 
> that this cap added ~87nH of inductance to the coil.
>
> Here are some pictures:
>
> http://home5.inet.tele.dk/f-hammer/bottom.jpg
>
> http://home5.inet.tele.dk/f-hammer/top.jpg
>
> http://home5.inet.tele.dk/f-hammer/top2.jpg
>
> http://home5.inet.tele.dk/f-hammer/detail.jpg
>
> Cheers, Finn Hammer